Update to 4.2.2

Changelog: https://github.com/NLnetLabs/nsd/releases/tag/NSD_4_2_2_REL

PR: 239964
Reported by: Jaap Akkerhuis <jaap@NLnetLabs.nl> (maintainer)
MFH: 2019Q3
Security: 56778a31-c2a1-11e9-9051-4c72b94353b5
Sponsored by: Netzkommune GmbH